Oil pulling has been known to help bad breath, and get rid of tonsil stones. I know you've had the surgery but you can read this article if you like because they talk about tonsil stone elimination and also about diets ect... Not only do they show 7 ways to get rid of them but other ways to prevent them for good.
This also may help the symptoms. Some people have used extra virgin coconut or other oils to help symptoms as well. But you have to have a little patience because the oil pulling detoxifies the body, which may cause the body to go through detox symptoms. If you have any rotting teeth or bacteria in the mouth it will kill it. It's also good for tooth aches and gum disease as well.
Just research different types of oils and what they do, especially extra virgin coconut oil and seasamee seed oil. If the odor doesn't go away with oil pulling then it's possible that may not be the problem. If you're constantly smelling it it may be in the nose area. http://tonsilstones.ca/5875/7stetst.pdf